printLocation: Add special support for minified documents

Author: IvanGoncharov

src/language/__tests__/printLocation-test.js

@@ -7,7 +7,48 @@ import dedent from '../../jsutils/dedent';
 import { Source } from '../../language';
 import { printSourceLocation } from '../printLocation';
 
-describe('printLocation', () => {
+describe('printSourceLocation', () => {
+  it('prints minified documents', () => {
+    const minifiedSource = new Source(
+      'query SomeMiniFiedQueryWithErrorInside($foo:String!=FIRST_ERROR_HERE$bar:String){someField(foo:$foo bar:$bar baz:SECOND_ERROR_HERE){fieldA fieldB{fieldC fieldD...on THIRD_ERROR_HERE}}}',
+    );
+
+    const firstLocation = printSourceLocation(minifiedSource, {
+      line: 1,
+      column: minifiedSource.body.indexOf('FIRST_ERROR_HERE') + 1,
+    });
+    expect(firstLocation + '\n').to.equal(dedent`
+      GraphQL request:1:53
+      1 | query SomeMiniFiedQueryWithErrorInside($foo:String!=FIRST_ERROR_HERE$bar:String)
+        |                                                     ^
+        | {someField(foo:$foo bar:$bar baz:SECOND_ERROR_HERE){fieldA fieldB{fieldC fieldD.
+    `);
+
+    const secondLocation = printSourceLocation(minifiedSource, {
+      line: 1,
+      column: minifiedSource.body.indexOf('SECOND_ERROR_HERE') + 1,
+    });
+    expect(secondLocation + '\n').to.equal(dedent`
+      GraphQL request:1:114
+      1 | query SomeMiniFiedQueryWithErrorInside($foo:String!=FIRST_ERROR_HERE$bar:String)
+        | {someField(foo:$foo bar:$bar baz:SECOND_ERROR_HERE){fieldA fieldB{fieldC fieldD.
+        |                                  ^
+        | ..on THIRD_ERROR_HERE}}}
+    `);
+
+    const thirdLocation = printSourceLocation(minifiedSource, {
+      line: 1,
+      column: minifiedSource.body.indexOf('THIRD_ERROR_HERE') + 1,
+    });
+    expect(thirdLocation + '\n').to.equal(dedent`
+      GraphQL request:1:166
+      1 | query SomeMiniFiedQueryWithErrorInside($foo:String!=FIRST_ERROR_HERE$bar:String)
+        | {someField(foo:$foo bar:$bar baz:SECOND_ERROR_HERE){fieldA fieldB{fieldC fieldD.
+        | ..on THIRD_ERROR_HERE}}}
+        |      ^
+    `);
+  });
+
   it('prints single digit line number with no padding', () => {
     const result = printSourceLocation(
       new Source('*', 'Test', { line: 9, column: 1 }),

src/language/printLocation.js

@@ -30,14 +30,37 @@ export function printSourceLocation(
 
   const columnOffset = sourceLocation.line === 1 ? firstLineColumnOffset : 0;
   const columnNum = sourceLocation.column + columnOffset;
+  const locationStr = `${source.name}:${lineNum}:${columnNum}\n`;
 
   const lines = body.split(/\r\n|[\n\r]/g);
+  const locationLine = lines[lineIndex];
+
+  // Special case for minified documents
+  if (locationLine.length > 120) {
+    const sublineIndex = Math.floor(columnNum / 80);
+    const sublineColumnNum = columnNum % 80;
+    const sublines = [];
+    for (let i = 0; i < locationLine.length; i += 80) {
+      sublines.push(locationLine.slice(i, i + 80));
+    }
+
+    return (
+      locationStr +
+      printPrefixedLines([
+        [`${lineNum}`, sublines[0]],
+        ...sublines.slice(1, sublineIndex + 1).map(subline => ['', subline]),
+        [' ', whitespace(sublineColumnNum - 1) + '^'],
+        ['', sublines[sublineIndex + 1]],
+      ])
+    );
+  }
+
   return (
-    `${source.name}:${lineNum}:${columnNum}\n` +
+    locationStr +
     printPrefixedLines([
       // Lines specified like this: ["prefix", "string"],
       [`${lineNum - 1}`, lines[lineIndex - 1]],
-      [`${lineNum}`, lines[lineIndex]],
+      [`${lineNum}`, locationLine],
       ['', whitespace(columnNum - 1) + '^'],
       [`${lineNum + 1}`, lines[lineIndex + 1]],
     ])